Method for reducing pyrophoricity of uranium hydride powdersion



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2,712,979 Raterited July 12, 1955 Mnrnon non nnnucnu; Prnorrronrcrr onURANTUM nvnmnn rownnn Thomas R. P. Gibb, J12, Marblehead, lViass., andWilliam Pasfieid, torrs, Conn, assignors, by mesne assign= ments, to theUnited States of America as represented by the United States AtomicEnergy l'ommission No Application February 27, 1952, Serial No. 273,764

2 Qlaims. (Ci. 23-145) This invention relates to powders, such asuranium hydride, which are pyrophoric and, more particularly, to amethod for reducing the pyrophoricity of such powders.

It is Well known that uranium hydride powder is highly pyrophoric, thatis, will ignite upon contact with air. Uranium hydride may be producedby subjecting uranium metal to the action of hydrogen in a closed retortheated to a suitable temperature. As the uranium metal becomes hydrided,the hydride separates from the metal in the form of a finely dividedpowder. When the uranium metal has been completely hydrided, the retortand its contents are cooled to normal room temperature, that is, toabout 20 C.

if the retort now should be opened for the purpose of removing theuranium hydride, the latter would come in contact with air andimmediately become ignited. Con-- sequently, it has been necessary toreplace the hydrogen in the retort by an inert gas, such as argon, andto transfer the uranium hydride from the retort to its place of storagein an inert atmosphere, such as argon. it also had to be maintained insuch an atmosphere during storage.

The present invention is based upon the discovery that the pyrophoricityof uranium powder is reduced so that it can be handled safely in air ifthe powder has been in contact with the vapor of triethylarnine atnormal room temperature. Other compounds efiective for this purpos: arebasic organic compounds selected from the group consisting of the otheraliphatic amines in which the ratio of the number of carbon atoms to thenumber of nitrogen atoms is not greater than about six, such astrimethylamine, and aliphatic others in which the ratio of the number ofcarbon atoms to the number of oxygen atoms is not greater than aboutsix, such as diethyl ether, dimethyl ether, ethyl methyl ether, etc. Bythe term basic organic compound, we mean an organic compound having afree pair of electrons (usually on the oxygen or nitrogen atom) which itcan use in a dative type bond with certain other compounds.

One method for reducing the pyrophorieity of uranium hydride powder soit can be handled safely in air, therefore, comprises bringing theuranium hydride powder in contact with the vapor of a basic organiccompound of the type above mentioned, preferably, at normal roomtemperature, that is, at a temperature not greater than about 20 C., fora suitable period of time. The period of time required for optimumresults varies from a few seconds to between two and three hoursdepending upon the volatility of the organic basic compound used. Analternative method comprises treating the powder with the basic organiccompound in liquid form and then permitting the liquid to evaporate,preferably, at room temperature.

Our investigations have been limited to the treatment of uranium hydrideand cerium hydride but we believe the invention may be applicable fortreating other metal hydride powders which normally are pyrophoric.

The invention is illustrated further by the following specific example.A thin layer of uranium hydride powder was placed in the bottom of asmall test tube in a dry box in an atmosphere of argon. A few drops oftriethylamine were placed on absorbent cotton and the cotton wedged intothe tube above the powder. After about two and one-half hours, the testtube was removed from the dry box and the cotton was removed from thetube. The uranium hydride powder then was poured from the tube in airupon a concrete surface and the powder was rubbed with the bottomsurface of the test tube without ignition of the powder.

We claim:

1. The method for reducing the pyrophoricity of uranium hydride powderwhich comprises bringing in contact with the powder the vapor of analiphatic amine in which the ratio of the number of carbon atoms to thenumber of nitrogen atoms is not greater than six.

2. The method for reducing the pyrophoricity of uranium hydride powderwhich comprises bringing the vapor of triethylamine in contact with thepowder.

References Cited in the file of this patent Newton et al., Nucleonics,vol. 4, No. 2, February 1949, pages l724 at p. 22. (Copy in ScientificLibrary.)

1. THE METHOD FOR REDUCING THE PYROPHORICITY OF URANIUM HYDRIDE POWDERWHICH COMPRISIES BRINGING IN CONTACT WITH THE POWDER THE VAPOR OF ANALIPHATIC AMINE IN WHICH THE RATIO OF THE NUMBER OF CARBON ATOMS TO THENUMBER OF NITROGEN ATOMS IS NOT GREATER THAN SIX.